As a method for producing beverage filled in a PET bottle, known in the art is a method called “hot pack”. As examples of the hot pack can be cited Japanese Patent Application Laid-open Publication No. 2001-278225 and Japanese Patent Application Laid-open Publication No. Hei 8-309841.
According to this method, acidic drink (pH less than 4.6) which has been heated to 85-95° C. or low-acidic beverage (pH 4.6 or over) is filled in a PET bottle whose heat resistance property has been improved by crystallizing its neck portion and, after sealing the bottle, the bottle is laid down to cause contents of the bottle to contact the neck portion and the cap portion of the bottle to thereby sterilize these portions and then the bottle is cooled in a cooling pasteurizer to provide a drink product.
Since, as described above, in the method for producing beverage filled in a PET bottle, contents liquid is generally filled in a PET bottle at a high filling temperature of 85-95° C., a PET bottle with a crystallized neck portion which has sufficient heat resistance at this filling temperature must be used and a PET bottle which is not crystallized in its neck portion cannot be used. Since the cost of the PET bottle with a crystallized neck portion is higher than the PET bottle with a non-crystallized neck portion, acidic and low-acidic beverages filled in a PET bottle by hot pack have the disadvantage that manufacturing cost of such beverages is high.
Moreover, hot pack requires a process for laying down a bottle after sealing it for sterilizing its neck and cap portions and this process takes extra time and, further it requires cooling time for the hot bottle to be cooled off during cooling by a cooling pasteurizer with the result that production efficiency is deteriorated.
Further, in beverage filled in a container such as beverage filled in a PET bottle in which contents can be seen from outside, reduction in the capacity of the contents can be recognized by the liquid surface level and, therefore, completeness of sealing can be recognized by observing the liquid surface level of the product after sealing. Since when a head space portion of a product is large, it will give the consumer an impression that quantity of drink is rather small, there is a demand on the side of a manufacturer that the liquid surface level of a drink should be raised to the maximum extent possible. Since, however, hot pack requires a high filling temperature, the liquid surface level after sealing drops substantially with resulting enlargement in the head space and this tends to give the impression that quantity of the drink is small.
The invention has been made in view of such disadvantages of the prior art high temperature filling method in a drink filled in a PET bottle. It is a first object of the invention to provide a method for production according to which contents filled in a container can be produced without using a polyester container with a crystallized neck portion such as a PET bottle with a crystallized neck portion.
A second object of the invention is to provide a method for producing contents filled in a container such as beverage filled in a bottle which does not require such time in laying down a container and cooling the container as in hot pack whereby production efficiency can be improved.
A third object of the invention is to provide a method for producing contents filled in a container according to which completeness of seal of a container can be recognized by observing the liquid surface level of the product while substantial drop in the liquid surface can be prevented.
Studies and experiments made by the inventors of the present invention for achieving these objects of the invention have resulted in the finding, which has led to the present invention, that, by introducing a polyester container with a non-crystallized neck portion into a sterilized closed space, sterilizing at least the inner surface of the container by wet heating using heated water and/or steam and then filling contents in the sterilized container at a filling temperature within a range from 40° C. to a temperature less than glass transition temperature which is determined by moisture content of the container and then sealing the container, sufficient sterility on a commercial basis can be secured even at a temperature within a range which is below the filling temperature of 85-95° C. according to the prior art hot pack method.
A method of producing contents filled in a container achieving the above described objects of the invention comprises steps of introducing a polyester container with a non-crystallized neck portion into a sterilized closed space in which entire inner surface of the sterilized closed space and surface of an apparatus disposed in the sterilized closed space are sterilized by wet heating of the space using heated water and/or steam and which is kept under a positive pressure by sterilized air; heating and sterilizing the container at least in its inner surface by wet heating using hot water and/or steam; and filling the contents in the sterilized container at a filling temperature within a temperature range from 40° C. to a temperature less than glass transition temperature which is determined by moisture content of the container and then sealing the container.
According to the invention; by heating and sterilizing the container at least in its inner surface by wet heating using hot water and/or steam and thereafter filling the contents in the sterilized container at a filling temperature within a temperature range from 40° C. to a temperature less than glass transition temperature which is determined by moisture content of the container, sufficient sterility on a commercial basis can be secured and, therefore, it becomes possible to use a polyester container with a non-crystallized neck portion. Further, since the filling temperature is substantially lower than that in the prior art hot pack, time required for cooling after sterilization can be shortened and, as a result, production efficiency can be greatly improved. Further, since the neck portion and the cap portion of the container can be sterilized by the wet heating of the container, the process of laying down the container after filling contents and sealing the container for sterilizing the neck portion and the cap portion of the container can be obviated and, as a result, production efficiency can be further improved. Furthermore, since the filling temperature is substantially lower than in hot pack, reduction in the capacity of the contents after cooling of the container is small and the liquid surface level can be raised as compared with a product by hot pack and this gives satisfaction to the consumer and completeness of seal of the container can be recognized.
Further, according to the invention, since in the space comprising at least space in which a bottle sterilizing process is performed, space in which a filling process is performed and space in which a sealing process is performed, entire inner surface of the space and surface of an apparatus disposed in the space are sterilized by wet heating of the space using heated water and/or steam, and at least the space in which the filling process is performed and the space in which the sealing process is performed are kept under a positive pressure by sterilized air, a rinsing process and a rinsing equipment after sterilizing the space which are required in the prior art method of spraying a sterilizer become unnecessary and, therefore, cost for such equipment can be obviated while a sterilized environment which is equivalent to the prior art one can be maintained.
According to one aspect of the invention, sterilization of the surface of the apparatus in the sterilized closed space is performed by wet heating sterilization in such a manner that surface temperature of the surface to be sterilized will become 60° C. or over and less than 80° C.
According to another aspect of the invention, the container introduced into the sterilized closed space is introduced into the sterilized closed space after being subjected in the outer surface of the container to wet heating sterilization using heated water and/or steam.
According to this aspect of the invention, since the container is sterilized by wet heating in its outer surface in the outside of the sterilized closed space and then is introduced into the sterilized closed space in which at least the inner surface of the container is sterilized with hot water, the container is introduced into the sterilized closed space in a state in which mold and bacteria which are of a high contamination degree have been sterilized and, as a result, amount of mold and bacteria introduced into the sterilized closed space is greatly reduced and possibility of mold and bacteria depositing again on the container after sterilization of the inner surface thereof is reduced to the maximum extent possible whereby sterilization of the inner and outer surfaces of the container can be achieved in the most efficient manner.
According to another aspect of the invention, the process of sterilizing the outer surface of the container introduced into the sterilized closed space is performed by wet heating sterilization in such a manner that heated water and/or steam is injected from a heated water injection nozzle or a steam injection nozzle onto the container so that temperature of the outer surface of the container will become 63° C. or over and less than 80° C.
According to another aspect of the invention, the process of sterilizing the outer surface of the container introduced into the sterilized closed space is performed in an outer surface sterilizing chamber which communicates with the sterilized closed space and is provided with an entrance and an exit of the container.
According to another aspect of the invention, the outer surface sterilizing chamber is filled with steam.
According to another aspect of the invention, the process of sterilizing at least the inner surface of the container is performed by wet heating sterilization in such a manner that temperature of the inner surface of the container will become 63° C. or over and less than 80° C.
According to another aspect of the invention, the moisture content of the container is moisture content of the non-crystallized neck portion of the container.
In manufacturing, a neck portion of a polyester container such as a PET bottle which is substantially not crystallized and not drawn is a portion which has the least heat resistance in the container. It is therefore important for preventing distortion of the neck portion due to heat that filling is made at a filling temperature which will be less than glass transition temperature determined by moisture content of the neck portion of the container. The same is the case with a neck portion of a polyester container such as a PET cup made by sheet forming which is drawn but not crystallized in manufacturing thereof.
According to another aspect of the invention, the method further comprises a process of reducing moisture content of the container before filling the contents in the container.
There is correlationship as shown in FIG. 7 between the glass transition temperature of the container such as a PET bottle with a non-crystallized neck portion and the moisture content of the container and the lower the moisture content of the container, the higher the glass transition temperature of the container. Therefore, in a case where sterilization should be made at a higher temperature for achieving sufficient sterilization, there may be a need for reducing the moisture content of the container so that the glass transition temperature of the container will become as high as possible. According to this aspect of the invention, the glass transition temperature of the container can be elevated to such a level as to exceed a necessary sterilization temperature by reducing the moisture content of the container.
According to another aspect of the invention, the method further comprises a process of forming a preform of the container, a process of forming the preform to the container and a process of reducing moisture content of the preform before forming the preform to the container. By reducing the moisture content of the preform of the container, the glass transition temperature of the container can be elevated to a higher temperature than in the case of reducing the moisture content of the container only.
The process of reducing the moisture content of the container and the preform of the container can preferably be made by dehumidifying the container. More specifically, the container and the preform of the container may be dehumidified by a dehumidifier or, alternatively, the container and the preform of the container may be kept in a humidity controlled room such as a drying room.
According to another aspect of the invention, after the container is formed, the formed container is transferred directly to the process of sterilizing at least the inner surface of the container in the sterilized closed space, or the outer surface sterilizing process of the container to be introduced into the sterilized closed space. By this arrangement, time required from forming of the container to sterilization of the container can be shortened and amount of humidity which the container absorbs from the outer environment is thereby reduced and, as a result, the moisture content of the container can be maintained at a low level to that extent.
According to another aspect of the invention, after the container is formed, the formed container is transferred directly to the sterilizing process and forming of the container is performed in an outer environment controlled space. By this arrangement, sterility of the container can be further improved.
According to another aspect of the invention, the method further comprises a process of forming a preform of the container and a process of forming the preform to the container wherein the formed preform is directly transferred to the process of forming the preform to the container.
According to another aspect of the invention, forming of the preform, transferring of the preform to the container forming process and forming of the container are performed in an outer environment controlled space.
According to still another aspect of the invention, the outer environment controlled space is Class 100,000 or below.
As described above, according to the invention, after at least the inner surface of the container is sterilized by wet heating, contents are filled in the container at a filling temperature within a temperature range from 40° C. to less than glass transition temperature which is determined by moisture content of the container whereby sufficient sterility on a commercial basis can be secured and, therefore, a polyester container with a non-crystallized neck portion having glass transition temperature within this temperature range can be used. Since the filling temperature is by far lower than the filling temperature of the prior art hot pack, time required for cooling after sterilization can be shortened and, as a result, production efficiency can be improved. Further, since the neck portion and the cap portion of the container are sterilized by wet heating sterilization of the container, the process of laying down the container after filling of the contents and sealing of the container for sterilizing the neck portion and the cap portion of the container can be obviated whereby production efficiency can be further improved. Furthermore, since the filling temperature is by far lower than the filling temperature of hot pack, reduction in the capacity of the contents after cooling of the container is small and the liquid surface level can be elevated as compared with hot pack and this give satisfaction to the consumer and completeness of seal of the container can be recognized.
Further, according to the invention, since in the sterilized closed space in which at least the inner surface is sterilized with heated water, entire inner surface of the space and surface of an apparatus disposed in the space are sterilized by wet heating of the space using heated water and/or steam, and the space is kept under a positive pressure by sterilized air, a rinsing process and a rinsing equipment after sterilizing the space which are required in the prior art method of spraying a sterilizer become unnecessary and, therefore, cost for the equipment can be obviated while a sterilized environment which is equivalent to the prior art one can be maintained.
According to one aspect of the invention, since the container is sterilized by wet heating in its outer surface in the outside of the sterilized closed space and then is introduced into the sterilized closed space in which at least the inner surface of the container is sterilized with hot water, the container is introduced into the sterilized closed space in a state in which mold and bacteria which are of a high contamination degree have been sterilized and, as a result, amount of mold and bacteria introduced into the sterilized closed space is greatly reduced and possibility of mold and bacteria depositing again on the container after sterilization of the inner surface thereof is reduced to the maximum extent possible whereby sterilization of the inner and outer surfaces of the container can be achieved in the most efficient manner.
There is correlationship between the glass transition temperature of the container such as a PET bottle with a non-crystallized neck portion and the moisture content of the container and the lower the moisture content of the container, the higher the glass transition temperature of the container. Therefore, in a case where sterilization should be made at a higher temperature for achieving sufficient sterilization, there may be a need for reducing the moisture content of the container so that the glass transition temperature of the container will become as high as possible. According to one aspect of the invention, the glass transition temperature of the container can be elevated to such a level as to exceed a necessary sterilization temperature by reducing the moisture content of the container.
According to one aspect of the invention, by shortening time required from forming of the container to filling of the contents, amount of humidity which the bottle absorbs from the outer environment is reduced and the moisture content of the bottle can be maintained at a low level to that degree.